The search functionality in DDB is just unprofessional.

I search for "Equipment", and I get a list of results that mention "equipment", like the Barbarian starting equipment, instead of having the Equipment chapter of the Player's Handbook as the first result.

You need to change your search functionality to use a professional index that will prioritize main sections over smaller ones, and main books over supplements or adventures.
The current search functionality is so bad, it takes less time to just open the book and browse through it than using the search.
It's even worse on the mobile app, because the small screen makes it harder to browse.

Consult with an information specialist on how to build a professional search functionality.

I imagine the search function is pretty complex on the back end.

If it was, for example, universal that everyone had all the books - then it'd probably be much easier.

But everyone who is on here may have unique cases, where some own zero books. They just have characters in campaigns. Maybe a few own PHB. But none own DMG. But the DM owns DMG, and six other sourcebooks.

The search function has to understand how to "parse" all of that information, for each unique person's access.

And honestly, the word "equipment" for D&D Beyond is like searching for "sex" on the internet and disappointed your favorite site didn't come up first. :)

Quote from SirTawmis>>

I imagine the search function is pretty complex on the back end.

If it was, for example, universal that everyone had all the books - then it'd probably be much easier.

 If the search did any kind of filtering based on your content, you might have a point, but it will give results for books you don't have.